Method of preserving rubber



ran name, or comranr, or

. OHIO, ASSIGNOR TO THE GOODYEAR TIRE & RUBBER RON, OHIO, A OTION OF OHIO V manat on or ransaavme anneal-t No Drawing. Oriel My invention relates to the manufacture of rubber products and it has particular reference to a method for improving the physical pro erties thereof.

his application is a, division of application Serial No. 151,825, filed Novem er 30, 1926.-

It is universally-achiowledged that vulcanized caoutchouc compositions deteriorate w when exposed to air, sunlight, and moisture, and that such deterioration exhibits itself by Y a loss in the tensile strength, resiliency, and other desirable properties. of the material. The effects accompanying the various delew terious reactions are known as agin and compounds which retard or partial y prevent the deterioration are termed antioxidents.

The object of the invention resides in the provision of a class of chemicalcompounds which may be incorporated with rubber com: positions to retard the aging phenomena.

More specifically, the invention contemplates the employment, in rubber composi tions, of the reaction products of naphthol with amines te serve as antioxidants. The following specific compounds have been found to possess, to a marked degree, the properties of the general class, and they are illustrative of the principles of the invention.

Example 1.'Phenyl 'beta-naphthylamine. This compound may be readily prepared by the reaction of beta naphthol with aniline.

Beta-naphtha] application filed. November 30, 1926, Serial No. 151,825. Divided and this application filed March 9,

1929. Serial 'No. 345,899.

colorless plates, having a melting point between 108 and 109 C.

The product was tested in stocks of the following composition; two percent of the antioxidant, based on the rubber content, being employed in both cases.

A B Rubber 56.00% 60.00% Zinc oxide 15.00 5.00 Gas black 23.00 25.00 Sulphur 1.60 1.80 Mineral rubber 3.20 5.00 Diphenylguanidine 1.20 Mercaptobenzothiazole 0.50 Stearic acid 2.70

The results of the aging test are indicated in Table I:

an t 811 t in E. i: p i'celi t el o li g d on. kgs /cm In all cases the compounds were cured for thlrty mmutes at a temperature correspondmg to 40 lbs. per square inch gauge steam pressure.

NHCl l Emample 2.--Phenyl alpha-naphthylamine. This material may be prepared from alphanaphthol and aniline, using the same procedure as that previously described. The product separates as practically colorless crystals havin a melting point between 62 and" 63 C. is material was tested in a stock having substantially the following composition, and the results are indicated in the appended Table II.

Parts Rubber 85.00 Iron oxlde 1.65 Lime 1.00 Magneslum oxide 1.00 Magnesium carbonate 50.00 Pine tar o1l 2.50 Antioxidant- 0.30

Table II After six days Original Percent at 50 C of origi- Cure nalqten- S! B Tensile Elon- Tensile Elonstrength gation strength gation Strength Min; 71 s 2 7 2.2 225 95 30 s c antwxldanb" 120 73. 1 268 49. 5 50 68 Tensile strength in kgs./cm'-.

Elongation in percent.

Example 3.Diamino-diphenyl di-betanaphthyl methane. Two mols of beta-naphthol Will react with formaldehyde in the presence of a condensing agent, such as sodium acetate, to form methylene di-betanaphthol, according to the following reaction.

(Ber 39: 439).

rubber composition containing the following ingredients:

. Parts Rubber-acetone' extracted 100 .0 Zinc oxide 5.0 Sulphur 3.0 I-Iexamethylene tetramine 1.0 Stearic acid 1.5

The test showed results-set forth in Table III.

Table'III After 6 days at Orlgmal 50 0. 150# 02 Cure Tensile Elon- Tensile Elonstrength gation strength gation N0 antioxidant--- 155 855 Melted down 50 min. at 40;? With antioxidant. 150 850 160 820 50 min. at 40)? OH OH HO 2 HCHO -r -I- .Methylene di-beta-naphtliol.

This product may be made to react with. amines to form compounds havingv antioxidant properties, according to the following reaction:

thereof should be limited to the specific compounds enumerated above, but only such limitations should be imposed as are set forth in the following claims.

NHCuHs CaHaHN Diamino diphenyl di-beta-naphthyl methane What I claim is l. A method of preserving rubber which comprises subjecting it to vulcanization in the presence of phenyl-beta-naphthylamine.

2. A rubber product that has been vu1-' canized in the presence of phenyl-beta naphthylamine.

In Witness whereof, I have hereunto signed my name.

Signedat Akron, in the county of Summit and State of Ohio, U. S. A., this 8th day of March, 1929.

JAN TEPPEMA. 

